[alsa-devel] [FFADO-devel] [PATCH 18/39] firewire-lib: Add a fallback at RCODE_CANCELLED

Jonathan Woithe jwoithe at just42.net
Tue Mar 4 02:35:35 CET 2014

On Sat, Mar 01, 2014 at 03:20:50PM +0100, Stefan Richter wrote:
> On Mar 01 Takashi Sakamoto wrote:
> >> A related question:  Since FFADO applies 200 ms or more as FCP
> >> transaction timeout, shouldn't firewire-lib's fcp.c increase
> >> FCP_TIMEOUT_MS from 125 to 200 or more as well?
> > 
> > For this developing, I've spent much time with my test devices.
> > But I've never experienced disadvantages under FCP_TIMEOUT_MS=125msec.
> > So feel no importance.
> > 
> > If you feel this importance, please post your patch with proper reasons.
> This is mostly a question to the ffado-devel subscribers.  125 ms is of
> course enough for devices which comply with the specification in this
> regard.  The question is whether FFADO developers know of devices (or
> suspect devices) which exceed the standard 100 ms and need more like 200
> ms.

I've personally had nothing to do with devices utilising FCP transactions so
unfortunately I don't really know.  My feeling is that the authors of the
respective FFADO drivers would not have applied an FCP timeout of 200 ms if
there was no demonstrated need for it.  Therefore in the absence of other
evidence I would be assuming that there are devices which require the higher
timeout allowed for in FFADO's streaming code.  However, I don't know which
specific devices these might be.


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